Aircraft turbo engines, such as turbo jet engines on aircraft, are used in all areas of the world and in particular atmospherically polluted areas. In particular, a sandy environment having fine sand size grading has an adverse affect on the functioning of turbo jet engines since extremely fine particles of sand are sucked up by these machines and are thus confronted with the air flow which is also sucked up.
With reference to FIG. 1, these particles are brought to the base of the front face 1AM of the disk 1 of the turbine which rotates around the axis A. Secured to this disk 1 is a labyrinth 2 whose outer ribbings 2N constitute an obstacle to the leaks of the cool flow from the turbine. This labyrinth 2 is secured to the disk 1 by means of tie rods or several bolts 3 which clamp the foot 2P of the labyrinth 2 against the upper surface 1AM of the disk 1. A step 2R of the labyrinth 2 extends from the other side, that is towards the axis A of the unit, constituting a sort of inner crown. Some of the particles sucked up by the turbo jet engine accordingly strike this upper surface 1AM and become housed behind the step 2R of the labyrinth 2. Having regard to the fact that considerable centrifugal forces are exerted on these mechanical elements, the step is slightly bent and may tend to widen, that is be distanced from the axis A of the turbo jet engine and deviate from the upper surface 1AM of the disk 1. It can be easily understood that the particles can then be housed between the disk 1 and the labyrinth 2, namely between the upper surface 1AM of the disk and the lower surface 2AV of the labyrinth 2.
There are certain drawbacks to this particular situation, namely:
plastic warping of the bolts 3 linking the labyrinth 2 to the disk 1 resulting in a loss of tightness between these two elements;
presence of cracks, fissures or loss of fragments of the labyrinth 2, and
increase of the play between the step 2R of the labyrinth 12 and the disk 1 resulting in a leak concerning the ventilation flow of the vanes 4 of the turbine and thus causing heating of the latter.